Feed device for a mill



Feb. 25, 1941. J. A. ERICKSON FEED DEVICE FOR A HILL 2 Sheets-Sheet 1 Filed Jan. 7, 1938 F1 1 3mm JOHN A.EFUEK5EIN Patented Feb. 25, 1941 UNITED STATES PATENT OFFICE FEED DEVICE FOR A MILL John A. Erickson, Jackson, Mich.

Application January I, 1938, Serial No. 183,742

5 Claims. (Ci- 83-44) This invention relates to small hammer mills for grinding grain and the like and more particularly to a device for preventing weeds, grass, straw oversize or other foreign materials from clogging the entrance to the mill preventing the proper feeding of the material being acted upon.

The hammer mill in connection with which the present invention is described, is disclosed in my copending application Serial No. 104,635, 'filed October 8, 1936. In that structure there is disclosed a feed screw projecting into a hopper. However, it is found that straw, weeds. etc., wrap about the feed screw to such an extent that they hinder the proper feeding to the mill. The present invention eliminates the foregoing dlfliculties by providing a structure for parting straw, weeds or other foreign material, into a plurality of parts so that it may be fed into the mill.

An object of the invention is to associate with a feeding screw for a hammer mill or the like a device for parting foreign material disposed in the material being acted on by the mill.

Another object of the invention is to provide a shearing edge adjacent the feeding screw for a hammer mill for parting foreign material in the material to be acted on.

A still further object of the invention is to provide a vertically extending plate immediately over the feeding screw of a hammer mill or the like for guiding foreign matter in the material to be acted on into the feeding screw.

A still further object of the invention is to provide means adjacent the feeding screw and means on the feeding screw for cooperating to part oversize or foreign matter in the material being acted upon by the mill.

A still further object is to provide a device for limiting the feeding action of the screw.

These and other objects will be apparent from the following specification when taken with the accompanying drawings, in which Fig. 1 is an end elevation of the mill,

Fig. 2 is a plan of the portion of the mill showing the hopper and the feed screw together with the baiiie,

Fig. 3 is a side elevation of the mill,

Fig. 4 is a detailed view disclosing the feeding screw and its cooperation with the feeding adiustment plate, and

Fig. 5 is an end view of the feeding screw.

Reference may be made to my aforesaid application for a more complete disclosure of the hammer mill to which the present invention is applied. Referring particularly to the, drawings,

the reference character i indicates a base on which an electric driving motor 2 is mounted. Also secured to the base I at one end thereof is the housing 3 of the mill in which a hub 4 is disposed. The hub 4 receives and is connected to the motor shaft in driving relation. Projecting laterally from the hub 4 are three inner supporting spindles 5 to which are freely pivoted hammers 6.

Disposed about the hammers 6 is a circular 10 screen 'i which maintains the grain or the like being acted upon by the hammers 8 in the path of the hammers 6, and through which the ground material passes. Projecting from the center of the hub 4 is a feeding screw 8 which projects through the casing 3 into a hopper 8 holding the material to be acted upon by the mill. The feeding screw 8 is secured to the hub 4 by a set screw l0 and comprises a central spindle ll about which is disposed a discontinuous thread i6 20 which defines, in effect, an axial channel along the feeding screw 8. The channel is provided by removing from what would be a continuous thread a portion of each convolution thereof. The axial channel in the feeding screw 8 presents a cross-section ii for each convolution of the thread ii. The cross-sections I'i provide a plurality of teeth, the outer edges of which lead the inner edges thereof, when the feeding screw is rotated in its operative direction as shown in Fig. 5. Reference to Figs. 4 and 5 will also disclose that the removal of a portion of each convolution also exposes a plurality of cross-sections iii of the thread l6, which lead the cross-sections i1 and that also the outer edge of each crosssection I8 leads the inner edges of the cross-sections i8 when the feeding screw 8 is rotated in an operative direction.

Secured to the outer wall 25 of the hopper 9 is a baffle 26 which projects vertically from the feeding screw 8 and is in contiguous relation thereto. In actual practice the baflie 26 is in the neighborhood of one-sixteenth of one inch from the feeding screw 8. This distance may be slightly greater or less, but commercial ex- 45 pediency dictates that the distance of one-sixteenth of one inch is preferable as an average. Thus if there are any weeds, or straw, or other foreign matter or oversize material in the material in the hopper to be acted upon by the mill they will be sheared between the feeding screw 8 by the lower edge of the baflle 26 into small particles. In order to prolong the life of the feeding screw 8 and the baifle 26, the feeding screw 8 and the lower edge of the baffle 26 are case hardened.

As shown particularly in Fig. 1 the mill is provided with a feeding adjustment plate 21 in which there are various sized openings 28. A set screw 28 is provided for cooperating with corresponding holes for fixing any adjustment of the inlet openings to the mill provided by the openings 28. The openings 28 are of such a size that even the smallest one thereof the feed screw 8 projects therethrough.

In order to provide the proper agitation of the material in .the hopper 9 so that it will not cling together and form a cavity over the feed screw 8 and at the same time to provide a feed screw which will actually feed the grain when rotating at a high speed, as it does, when connected directly to the motor 2, the feed screw 8 must have a predetermined minimum pitch and depth of thread. A feed screw 8 of a predetermined minimum .pitch and depth of thread is also required to provide proper shearing cooperation with the baffle 28, to prevent grass, weeds, etc., from binding about it. It has been found, however, when the feed screw is designed thus and the smallest opening 28 just passes the screw 8 and the others are graduated larger to vary the input to the mill, that more material from the hopper 9 is fed to the mill than can be taken care of by the hammers 6. In order to overcome this difiiculty the construction illustrated in detail in Fig. 4 has been developed.

As shown in Fig. 4, the feed screw 8 is provided adjacent the inner end thereof with a collar which collar in operative position in the mill is within an opening 28 in the feeding adjustment plate 21. The collar 35 functions to limit .the amount of material that can be fed to the mill. Accordingly, with this construction the feeding screw 8 may have the desired pitch and depth of thread and yet not feed too much material into the mill. As will be observed from Fig. 4, the diameter of the collar 35 is and must be less than the diameter of the thread -i 8.

It will be clear from the foregoing description that the teeth on the feeding screw 8 provided by the chord section l1, while they have been shown as undercut and having straight faces they need not be necessarily undercut and need not have straight faces, but may be concave for instance. It will be seen that by the present invention I have provided a hammer mill of small capacity which will not only feed adequately but also will cut up any foreign material in the material to be acted upon thereby preventing it from clogging .the inlet to the mill.

The baffle 28 in addition to cooperating with the feeding screw 8 to part particles of foreign matter in the material in the hopper also acts to break up the material over the feeding screw and thus tend to eliminate the possibility of the material in the hopper arching over the feed screw. It should also be apparent that there is a direct cooperation between the baffles 26 and the collar 35 in that the use of ,the collar 35 permits a sufficiently large feeding screw 8 to satisfactorily part weeds, grass and other foreign matter in the material to be acted upon by the mill, while at the same time limiting the amount of the material fed to the mill from the hopper to an amount which can be ground by the mill.

The collar 35 is shown as a telescoping part. This is a convenient design for the reason that the feeding screw may be cheaply made by cutting a thread on a rod and cutting off the threads on a portion of the rod .to provide a shank portion. However, the collar 35- may be an integral part of the feeding screw if desired.

Having thus described my invention, what I desire to secure by Letters Patent and claim is:

1. A device of the character described, comprising a miller the like, a screw having threads for feeding material to be acted upon into said mill or the like, a hopper adjacent said mill into which said screw projects, and a baiile projecting from said screw and extending substantially axially thereof, said screw having shearing teeth, said screw having an axially extending section removed therefrom to expose the cross-sections of said threads which comprise said teeth, said baflle and teeth being in shearing relation for pariting oversize or foreign matter in said mater al.

2. A device of the character described, comprising a mill or the like having an inlet opening of a predetermined diameter, a feeding device projecting through said opening, comprising a screw having a predetermined diameter for feeding material into said mill or the like, said screw having teeth, a collar on said feeding device disposed in said inlet opening, said collar having a diameter less than that of the threads on said screw, said collar being for the purpose of limiting the amount of material fed into said mill by said screw, a hopper adjacent said mill into which said screw projects, and a baffle projecting from said screw and extending substantially axially thereof, said baille being in cooperating relation with said teeth for parting oversize or foreign matter in said material.

3. A device of the character described comprising a mill or the like having a hopper for holding granular material, an inlet opening of a predetermined diameter, from said hopper to said mill, a feeding device projecting through said opening comprising a screw having a predetermined substantially uniform diameter projecting into said hopper for feeding granular material into said mill or the like, said screw comprising threads on a shaft and a feed controlling collar on said feeding device disposed in said inlet opening, said collar having a diameter less than that of the diameter of the threads on said screw and greater than that in said shaft, said collar being for the purpose of limiting the amount of granular material fed into said mill by said screw while at the same time assuring sufiicient thread depth to provide adequate thread engagement with the granular material being fed.

4. A device of the character described comprising a mill or the like, a screw for feeding material to be acted upon into said mill or the like, said screw comprising a spindle having a helical thread thereon, a hopper adjacent said mill into which said screw projects, and a baille projecting from said screw and extending substantially axially thereof, said screw having teeth, said teeth being undercut in a direction from the periphery toward the screw axis, each of said teeth being preceded for a substantial distance in the direction of rotation by a smooth spindle portion, one edge of said baffle being in contiguous and shearing relation with said screw and teeth for parting oversize or foreign matter suc as straw in said material. I

5. A device of the character described comprising a mill or the like having a hopper, an inlet opening of a predetermined diameter, from said hopper to said mill, a feeding device procollar having a diameter less than that ofthe diameter of the threads on said screw, said collar being for the purpose of limiting the amount of material fed into said mill by said screw.

J OHN A. ERICKSON. 

